the leak was in the transmission coil leaking transmission fluid into the cooling water. I found pink foam in my radiator. I sent a sample of the fluid to a lab recommended by Allison. The after market cooler was installed into the piping running from the radiator to the engine and the transmission hoses were connected to the new cooler. the old transmission ports were plugged. the old cooler still has cooling fluid running through but no longer has transmission fluid running through it. the cooling system was flushed twice with Prestone radiator flush. I changed the transmission fluid and filters and all seems well after a 800 mile trip home. I hope this is helpful. Paul McLendon PS the cost of repairs was $ 4500.00

Ouch! Glad to hear that no transmission problems have surfaced.

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Tom, Patty, Hannah "The Big Dog" and Abby Kat, Indianapolis, Indiana 2000 36' FDS 72232 Our PhotosWe live out in our old van. Travel all across this land. Drive until the city lights dissolve into a country sky, me and you - hand in hand.

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It is EXTREMELY rare for a transmission cooler/engine coolant leak to be only one way.

Why?

When the engine is running, transmission fluid pressure exceeds coolant system pressure, so ATF ends up in the coolant.

When the engine is shut off, transmission pressure drops to zero. But the hot coolant and pressure radiator cap keep pressure on the coolant.

So, normal for any leak to be in BOTH directions.

Brett

And wouldn't plugging the system handle that?

Quote:

Originally Posted by cPaul

We have talked to an Allison Transmission repair shop. They do not know where if we need a transmission cooler to get one. So I am seeking any information I can find on what is in the coach and where we might got one. If there are any ideas what might be causing this pink foam mixture other than transmission fluid in it I would like to hear them. Thanks

I'd be will to give a call to someone who has good information on this subject cPaul

Not to pile on but since the OEM tranny cooler is integrated [inside] into the engine radiator, I assume "plugging" means you capped off the external ports on the OEM tranny cooler. But was also curious about the original internal cooler leak allowing residual tranny fluid to mix with the new coolant--unless you flushed both the old OEM cooler and the radiator before plugging the tranny cooler.....Still a mystery how tranny fluid got into the engine coolant but no coolant got into the tranny fluid--just lucky I guess??????